The long-term objective of this research is to develop a ciliated cell-specific promoter that will improve the effectiveness of gene therapy or cystic fibrosis (CF). In normal airways, the cystic fibrosis transmembrane conductance regulator (CFTR) protein is expressed primarily at the apical surface of ciliated cells and in the submucosal glands. For gene therapy of CF to be successful, the normal CFTR protein must be expressed in the proper location. However, many of the gene therapy vectors currently under investigation have no specificity for the differentiated airway epithelium. In addition, these vectors frequently use viral promoter elements or promoters of constitutively expressed genes to drive high-level expression of reporter genes. A major drawback to the use of these vectors therefore is that they may result in high levels of CFTR expression in unwanted cell types (e.g., macrophages, basal cells). These promoters may also be less efficient at providing stable, long-term expression in the non-dividing ciliated cell population. Our hypothesis is that the use of a specific promoter to direct expression of the CFTR protein to the ciliated cells located at the apical surface of the airways will correct the CF phenotype. In addition, we hypothesize that by using an endogenous promoter in an integrating vector, we will achieve stable long-term expression of the CFTR protein. The use of a ciliated cell-specific promoter will also increase the safety of gene therapy for CF by preventing potentially deleterious expression of CFTR in the wrong cell types. To test our hypothesis, we propose the following specific aims: Specific Aim 1: To identify and clone the promoter regions of ciliated cell-specific genes. Specific Aim 2: To identify the essential regulatory elements responsible for ciliated cell specific gene expression. Specific Aim 3: To demonstrate correction of the CF phenotype in both in vitro and in vivo models by targeted expression of the normal CFTR gene in ciliated cells.